Detailed Description

The QMultiMap class is a convenience QMap subclass that provides multi-valued maps.

QMultiMap<Key, T> is one of Qt's generic container classes. It inherits QMap and extends it with a few convenience functions that make it more suitable than QMap for storing multi-valued maps. A multi-valued map is a map that allows multiple values with the same key; QMap normally doesn't allow that, unless you call QMap::insertMulti().

Because QMultiMap inherits QMap, all of QMap's functionality also applies to QMultiMap. For example, you can use isEmpty() to test whether the map is empty, and you can traverse a QMultiMap using QMap's iterator classes (for example, QMapIterator). But in addition, it provides an insert() function that corresponds to QMap::insertMulti(), and a replace() function that corresponds to QMap::insert(). It also provides convenient operator+() and operator+=().

QMultiMap's key and value data types must be assignable data types. This covers most data types you are likely to encounter, but the compiler won't let you, for example, store a QWidget as a value; instead, store a QWidget *. In addition, QMultiMap's key type must provide operator<(). See the QMap documentation for details.